This invention relates in general to hazardous waste containment and in particular to selectively emplacing an impermeable polymeric barrier in the geologic substructure underlying a waste landfill to block the migration of waste from the landfill to the surrounding environment. It also relates to the polymeric barrier material itself.
A great concern exists today because hazardous wastes buried in landfills across the country are escaping into the environment. There are hundreds of hazardous waste landfills in the United States with documented leakage or concern about leakage. Known remedial measures to prevent the escape of waste from landfills are costly to implement and are of uncertain effectiveness. There is a critical need for affordable and effective techniques to seal leaking landfills and curtail continued environmental contamination.
Currently, efforts to control the escape of waste from leaking landfills include removing the waste, solidifying the waste, detoxifying the waste and containing the waste. The particular technique chosen varies necessarily with the character of the individual site. For example, thousands of pounds of toxic material are present at the S-area landfill in Niagara Falls, N.Y. Because the cost for removing these materials to another location are prohibitive, an extensive containment and treatment plan has been developed for the site. The plan calls for the installation of containment walls around the perimeter of the site from the surface down to the bedrock or clay below the waste and then for the placement of an impermeable cap over the top of the site. The perimeter walls will stop the lateral flow of waste materials out of the site while the cap will stop surface water and precipitation from percolating through the site and causing materials to leach out. The bedrock or clay base must be relied upon to arrest the downward leaching of waste materials into the groundwater containing layer.
The containment technologies available for forming vertical barriers around such sites include slurry walls, grout curtains and pilings. To be effective, the vertical barriers must be attached to a low permeability layer at the bottom. Typically the layer is the existing bedrock or clay. Sites where the bedrock or clay is fractured or is too far below the surface cannot be treated in this manner. Even where the vertical barriers are attached to a low permeability layer, concern exists regarding the effectiveness of this containment technique. Further expensive control measures are taken such as dewatering the site with collection wells and providing pumps along the perimeter walls to induce the flow of ground water up through the underlying strata of the site to stop any flow of contaminated water out of the landfill area. Furthermore, comprehensive monitoring activity typically is conducted to detect failure of the system. To date, no adequate technique for sealing the entire base of a landfill site has been developed.